You’re chatting with friends at a party and a waitress comes around with glasses of champagne. You drink one, then another, maybe even a few more. Before you realize it, you are laughing more loudly than usual and swaying as you walk. By the end of the evening, you are too slow to move out of the way of a waiter with a dessert tray and have trouble speaking clearly. The next morning, you wake up feeling dizzy and your head hurts. You may have a hard time remembering everything you did the night before.
These reactions illustrate how quickly and dramatically alcohol affects the brain. The brain is an intricate maze of connections that keeps our physical and psychological processes running smoothly. Disruption of any of these connections can affect how the brain works. Alcohol also can have longer-lasting consequences for the brain—changing the way it looks and works and resulting in a range of problems.
Most people do not realize how extensively alcohol can affect the brain. But recognizing these potential consequences will help you make better decisions about what amount of alcohol is appropriate for you.
WHAT HAPPENS INSIDE THE BRAIN?
The brain’s structure is complex. It includes multiple systems that interact to support all of your body’s functions—from thinking to breathing to moving.
These multiple brain systems communicate with each other through about a trillion tiny nerve cells called neurons. Neurons in the brain translate information into electrical and chemical signals the brain can understand. They also send messages from the brain to the rest of the body.
Chemicals called neurotransmitters carry messages between the neurons. Neurotransmitters can be very powerful. Depending on the type and the amount of neurotransmitter, these chemicals can either intensify or minimize your body’s responses, your feelings, and your mood. The brain works to balance the neurotransmitters that speed things up with the ones that slow things down to keep your body operating at the right pace.
Alcohol can slow the pace of communication between neurotransmitters in the brain.
DISCOVERING THE BRAIN CHANGES
There still is much we do not understand about how the brain works and how alcohol affects it. Researchers are constantly discovering more about how alcohol interrupts communication pathways in the brain and changes brain structure, and the resulting effects on behavior and functioning. A variety of research methods broaden our understanding in different ways:
BRAIN IMAGING – Various imaging tools, including structural magnetic resonance imaging (MRI), functional magnetic resonance imaging (fMRI), diffusion tensor imaging (DTI), and positron emission tomography (PET), are used to create pictures of the brain. MRI and DTI create images of brain structure, or what the brain looks like. fMRI looks at brain function, or what the brain is doing. It can detect changes in brain activity. PET scans look at changes in neurotransmitter function. All of these imaging techniques are useful to track changes in the alcoholic brain. For example, they can show how an alcoholic brain changes immediately after drinking stops, and again after a long period of sobriety, to check for possible relapses.
PSYCHOLOGICAL TESTS – Researchers also use psychological tests to evaluate how alcohol-related brain changes affect mental functioning. These tests demonstrate how alcohol affects emotions and personality, as well as how it compromises learning and memory skills.
ANIMAL STUDIES – Testing the effect of alcohol on animals’ brains helps researchers better understand how alcohol injures the human brain, and how abstinence can reverse this damage.
DEFINING THE BRAIN CHANGES
Using brain imaging and psychological tests, researchers have identified the regions of the brain most vulnerable to alcohol’s effects. These include:
CEREBELLUM – This area controls motor coordination. Damage to the cerebellum results in a loss of balance and stumbling, and also may affect cognitive functions such as memory and emotional response.
LIMBIC SYSTEM – This complex brain system monitors a variety of tasks including memory and emotion. Damage to this area impairs each of these functions.
CEREBRAL CORTEX – Our abilities to think, plan, behave intelligently, and interact socially stem from this brain region. In addition, this area connects the brain to the rest of the nervous system. Changes and damage to this area impair the ability to solve problems, remember, and learn.
ALCOHOL SHRINKS AND DISTURBS BRAIN TISSUE
Heavy alcohol consumption — even on a single occasion—can throw the delicate balance of neurotransmitters off course. Alcohol can cause your neurotransmitters to relay information too slowly, so you feel extremely drowsy. Alcohol-related disruptions to the neurotransmitter balance also can trigger mood and behavioral changes, including depression, agitation, memory loss, and even seizures.
Long-term, heavy drinking causes alterations in the neurons, such as reductions in the size of brain cells. As a result of these and other changes, brain mass shrinks and the brain’s inner cavity grows bigger. These changes may affect a wide range of abilities, including motor coordination; temperature regulation; sleep; mood; and various cognitive functions, including learning and memory.
One neurotransmitter particularly susceptible to even small amounts of alcohol is called glutamate. Among other things, glutamate affects memory. Researchers believe that alcohol interferes with glutamate action, and this may be what causes some people to temporarily “black out,” or forget much of what happened during a night of heavy drinking.
Alcohol also causes an increased release of serotonin, another neurotransmitter, which helps regulate emotional expression, and endorphins, which are natural substances that may spark feelings of relaxation and euphoria as intoxication sets in. Researchers now understand that the brain tries to compensate for these disruptions. Neurotransmitters adapt to create balance in the brain despite the presence of alcohol. But making these adaptations can have negative results, including building alcohol tolerance, developing alcohol dependence, and experiencing alcohol withdrawal symptoms.
WHAT FACTORS MAKE A DIFFERENCE?
Different people react differently to alcohol. That is because a variety of factors can influence your brain’s response to alcohol. These factors include:
HOW MUCH AND HOW OFTEN YOU DRINK – The more you drink, the more vulnerable your brain is.
YOUR GENETIC BACKGROUND AND FAMILY HISTORY OF ALCOHOLISM – Certain ethnic populations can have stronger reactions to alcohol, and children of alcoholics are more likely to become alcoholics themselves.
YOUR PHYSICAL HEALTH – If you have liver or nutrition problems, the effects of alcohol will take longer to wear off.
ARE BRAIN PROBLEMS REVERSIBLE?
Abstaining from alcohol over several months to a year may allow structural brain changes to partially correct. Abstinence also can help reverse negative effects on thinking skills, including problem-solving, memory, and attention.
OTHER ALCOHOL – RELATED BRAIN CONDITIONS
LIVER DAMAGE THAT AFFECTS THE BRAIN
Not only does alcoholic liver disease affect liver function itself, it also damages the brain. The liver breaks down alcohol—and the toxins it releases. During this process, alcohol’s byproducts damage liver cells. These damaged liver cells no longer function as well as they should and allow too much of these toxic substances, ammonia and manganese in particular, to travel to the brain.These substances proceed to damage brain cells, causing a serious and potentially fatal brain disorder known as hepatic encephalopathy.
Hepatic encephalopathy causes a range of problems, from less severe to fatal.These problems can include:
- Sleep disturbances
- Mood and personality changes
- Shortened attention span
- Coordination problems, including asterixis, which results in hand shaking or flapping
- Doctors can help treat hepatic encephalopathy with compounds that lower blood ammonia concentrations and with devices that help remove harmful toxins from the blood. In some cases, people suffering from hepatic encephalopathy require a liver transplant, which generally helps improve brain function.